NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: The Star of Bethlehem and Navigation
From: Frank Reed
Date: 2009 Jan 5, 16:59 -0800
From: Frank Reed
Date: 2009 Jan 5, 16:59 -0800
Mike Dorl, you wrote: "I start up my almanac program and put in the lat/log of Ugarit (35.8E 35.683N), set the date to 3/5/1223 BC and play with the time until I get the lunar distance of the sun as low as possible at 1152. I then have a separation of 4' 9.3". I diddle delta T which my program has set to 28404.763 and find I can get a closer approach at 11:50 with a delta T of 28460.000. So what am doing when I diddle delta T? The picture I have in my mind is a sphere with the path of the eclipse outlined on it with an overlay sphere with a map of the world on it. So by changing delta T I revolve the map about the earths axis relative to first sphere to bring Ugarit closer to the center of the path of the eclipse. So delta T is constrained to those values which bring Ugarit into the path of the eclipse. Is that an ok way to think about it? " That's just how I think about it. So you would want to adjust delta-T until Ugarit is on the east and then again on the west limits of the total eclipse path. Those would then be good limits on delta-T for that date. All of this assumes that the brief description on the tablet actually refers to a total eclipse, and the eclipse was seen at Ugarit exactly and not at some nearby place. And you wrote: "Hopefully my almanac has also made some reasonable adjustments for changes in the earths axis. Are those know well enough and predictable enough to project them 3000 years into the past?" The change in inclination shouldn't be a problem for historical dates. Things only get complicated, in my experience, when you deal with time periods of tens of thousands of years. -FER --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---